A Huygens’ surface approach to rapid characterization of peripheral nerve stimulation

Abstract

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Peripheral nerve stimulation informed design of a high‐performance asymmetric head gradient coil

“…Consequently, the Y + Z and Y − Z cases induce different E‐field patterns on different nerves, yielding different nerve activation maps and thresholds (the threshold differences were 10.3% in experiments and 23.7% in simulations). This effect has important implications for software designed to monitor the PNS characteristics of applied waveforms and warn the operator of potential stimulation, and may become more prominent in highly asymmetric coil designs such as those arising from explicit PNS optimization 34,47 …”

“…In contrast, the step-by-step PNS-informed design process relies on the coil designer's intuition, and the globally optimal design may not be part of the search space "spanned" by the traditional design constraints and the adjustments explored by the designer. This is emphasized by the fact that coil designs optimized by the P-matrix constrained BEM-SF approach tend to produce X-axis and Y-axis gradient coils with asymmetry in both the y-direction and z-direction 34,47 (many existing head gradients are asymmetric in the z-direction, but not the y-direction). The design process used in this work did not explore coil designs that were asymmetric in the y-direction.…”

“…This effect has important implications for software designed to monitor the PNS characteristics of applied waveforms and warn the operator of potential stimulation, and may become more prominent in highly asymmetric coil designs such as those arising from explicit PNS optimization. 34,47 The PNS-informed design process used in this work relied on constraining the relative B-field magnitude at target points in the head, spine, and shoulders as a way to create coil designs that differed in PNS thresholds but met all other constraints. A design could then be chosen based on the assessment by the PNS model.…”

Human prostate MRI at ultrahigh‐performance gradient: A feasibility study

“…Assuming evenly scaling G max and SR max from the values of current microstructure anatomy gradient for neuroimaging with ultrafast scanning (MAGNUS) operating at 1 MVA (i.e., 200 mT/m and 500 T/m/s), we can achieve: The peripheral nerve stimulation (PNS) is determined by both the electromagnetic field and the distribution of nerves. PNS-informed design of gradient coils [36][37][38] has emerged to achieve high PNS threshold, compared with whole-body gradient coils. With electromagnetic and neurodynamic simulations, it is feasible to design gradient coils achieving high PNS at prostate isocenter position.…”

Connectome 2.0: Developing the next-generation ultra-high gradient strength human MRI scanner for bridging studies of the micro-, meso- and macro-connectome

“…To achieve this goal, we are leveraging recently developed simulation tools for the accurate prediction of PNS thresholds using realistic whole-body human nerve models in combination with electric field simulations ( Davids et al, 2020a , b , 2017 , 2019 , 2021b ). As in the case of the Impulse head gradient ( Davids et al, 2021a ) ( Fig.…”